1. Field of the Invention
The present invention relates to a color image processing device which processes color image data generated by scanning an original document.
2. Description of the Related Art
A scanner device is used independently or loaded in a copy machine or the like to be used for, for example, converting an original document printed on paper into digital data. Recently, a color scanner device, which can scan an original document by color, is becoming widespread. For example, such a color scanner device includes line sensors for individually scanning each of a red component (R), a green component (G) and a blue component (B). In accordance with voltage values obtained from the line sensors, the color scanner device generates image data. Each of the RGB line sensors is provided in parallel to a main scanning direction at a prescribed interval between one another (hereinafter simply referred to as a “line gap”). Therefore, at a prescribed timing, each of the line sensors is scanning different lines on the original document, respectively. A line correction memory is provided for accumulating pixel data acquired from each of the line sensors. The pixel data of a preceding line sensor is loaded from the line correction memory with a delay. By composing the loaded pixel data, pixel data of a RGB format is generated for the same line. Then, by combining the pixel data of the RGB format generated for each line, image data of the original document is generated.
In case a sampling cycle of the line sensors is constant, a rate of magnification in a scanning process of the original document is determined by a relative transferring speed of sampling positions of the line sensors with respect to the original document. For example, when enlarging an original document, the transferring speed is decreased. When reducing an original document, the transferring speed is increased. Therefore, according to the transferring speed, there are cases in which each of the line sensors cannot scan the same line on the original document. When the pixel data acquired from each of the line sensors is composed in this case, the image quality deteriorates. As the technology for correcting such a gap in the scanning lines generated by enlarging or reducing a document, there is technology being proposed to change the sampling cycle and the time for starting a main scanning process in each of the line sensors.
According to the above-described conventional technology, the sampling timing of each of the line sensors (the time for starting the main scanning process) is controlled according to the rate of magnification. Therefore, the same line can be scanned at any rate of magnification. However, hardware for controlling the sampling timing for each of the line sensors is necessary to be provided in both the line sensors and the control circuit. The hardware cannot be shared and as a result, the device results in being expensive.